ob-R: Tidy up bits of the async implementation

* ob-R.el (ob-session-async-org-babel-R-evaluate-session): Use
defvaralias for `ess-eval-visibly-p' instead of modifying user-defined
variable.  Remove temporary declaration that silences the byte-compiler.

* ob-R.el (org-babel-R-evaluate,
ob-session-async-org-babel-R-evaluate-session, org-babel-R-evaluate):
Remove mentions of unused argument `result-params'.

lisp/ob-R.el

@@ -40,13 +40,6 @@
 (declare-function ess-wait-for-process "ext:ess-inf"
 		  (&optional proc sec-prompt wait force-redisplay))
 
-;; FIXME: Temporary declaration to silence the byte-compiler
-(defvar user-inject-src-param)
-(defvar ess-eval-visibly-tmp)
-(defvar ess-eval-visibly)
-(defvar ess-inject-source)
-(defvar user-inject-src-param)
-
 (defconst org-babel-header-args:R
   '((width		 . :any)
     (height		 . :any)
@@ -385,7 +378,7 @@ Has four %s escapes to be filled in:
   (if session
       (if async
           (ob-session-async-org-babel-R-evaluate-session
-           session body result-type result-params column-names-p row-names-p)
+           session body result-type column-names-p row-names-p)
         (org-babel-R-evaluate-session
          session body result-type result-params column-names-p row-names-p))
     (org-babel-R-evaluate-external-process
@@ -486,7 +479,7 @@ Insert hline if column names in output have been requested."
 (defconst ob-session-async-R-indicator "'ob_comint_async_R_%s_%s'")
 
 (defun ob-session-async-org-babel-R-evaluate-session
-    (session body result-type _ column-names-p row-names-p)
+    (session body result-type column-names-p row-names-p)
   "Asynchronously evaluate BODY in SESSION.
 Returns a placeholder string for insertion, to later be replaced
 by `org-babel-comint-async-filter'."
@@ -525,7 +518,8 @@ by `org-babel-comint-async-filter'."
     (output
      (let ((uuid (md5 (number-to-string (random 100000000))))
            (ess-local-process-name
-            (process-name (get-buffer-process session))))
+            (process-name (get-buffer-process session)))
+           (ess-eval-visibly-p nil))
        (with-temp-buffer
          (insert (format ob-session-async-R-indicator
 			 "start" uuid))
@@ -534,13 +528,7 @@ by `org-babel-comint-async-filter'."
          (insert "\n")
          (insert (format ob-session-async-R-indicator
 			 "end" uuid))
-         (setq ess-eval-visibly-tmp ess-eval-visibly)
-         (setq user-inject-src-param ess-inject-source)
-         (setq ess-eval-visibly nil)
-         (setq ess-inject-source 'function-and-buffer)
-         (ess-eval-buffer nil))
-       (setq ess-eval-visibly ess-eval-visibly-tmp)
-       (setq ess-inject-source user-inject-src-param)
+         (ess-eval-buffer nil ))
        uuid))))
 
 (defun ob-session-async-R-value-callback (params tmp-file)